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The development of broad-spectrum ultraviolet- and visible-light photocatalysts constitutes one of the most significant challenges in the field of photocatalytic pollutant removal. Here, the efficiency of the directly prepared nitrogen-doped quantum zeolitic imidazolate framework (ZIF)-8-dot catalyst for the photocatalytic degradation of the methylene blue dye was reported. The prepared catalysts were characterized using Brunauer-Emmett-Teller, X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy techniques. Under sunlight irradiation, the 1% nitrogen-doped quantum-ZIF-8-dot catalyst showed 75% photodegradation in half an hour and ≈93% photodegradation after 3 hours compared to ≈87% for the ZIF-8 metal-organic framework. The high performance of the 1% nitrogen-doped quantum-ZIF-8-dot catalyst was attributed to the synergism between the catalyst components, upconverted fluorescence property of nitrogen-doped quantum dots, and charge (electrons-holes) separation. The reactive radical test revealed that the hydroxyl radical was dominant. The step-scheme heterojunction mechanism for photocatalytic degradation was also deduced. The kinetic study through the photocatalytic isotherms revealed that the pseudo-first-order kinetic model can describe the reaction mechanism.

CuInSe2 I–III–VI2 ternary semiconductor considered as one of the most promising semiconductor material which considers a very efficient solar energy conversion material. An organometallic pyrolysis method is used to prepare monodisperse CuInSe2 nanoparticles using a mixture of oleylamine, and trioctylphosphine (TOP) as capping materials. Controlling the particle shape dot, rods or flowers occurs via varying the reaction temperatures (160, 200, 220°C) respectively. The obtained particles have been characterized to determine the shape and size of CuInSe2 nanoparticles using HR-TEM and XRD. The optical and the electronic properties of these particles have been investigated and discussed in details. Then the different shapes of CIS nanoparticles (nanodots, nanorods, and nanoflowers) were introduced to the DSSC to study their effect on the optical switching properties. It was found that the nanoflowers provide better photovoltaic performance than the other shapes; since it reduces the settling time to 50 milliseconds after it was more than 17 second before adding CIS nanoparticles to the cells.

Silver nanoparticles have shown success in many applications, especially in the field of biochemistry, by controlling the shape and size of these nanoparticles, which had a significant impact on the diversity of their antimicrobial properties. Many different shapes and sizes of silver nanoparticles can be prepared by various techniques, the most important of which is the use of capping agents, where the role of capping agents is not limited to controlling both sizes and shape only but extends to the stability of nanoparticles nanostructures. In addition, the type of capping agent has an influential role in the surface efficiency of the formed silver nanoparticles. However, multiple concerns have been raised regarding the environmental safety and human health impacts of the use of chemically manufactured capping agents. This review included the manufacture of silver nanoparticles using aqueous extract of some plants, flowers, or fruits, and their applicability and activity in various fields such as antioxidants and antibacterials were examined. Also, some of the most common and popular chemical and physical methodologies are initially described, and the advantages and disadvantages of using these methods to prepare silver nanoparticles are considered. Green synthesis methodologies have been discussed in detail with emphasis on their benefits and applications. Much of the recent literature related to the use of plant extracts have been addressed, and the effects of basic reaction parameters, such as temperature, pH, precursor, and extract concentration, on silver nanostructure size and morphology have been reported. Moreover, current challenges related to the green synthesis of silver nanostructures and future directions have been identified. In summary, the review aims to demonstrate the true potential of green nanotechnology towards the synthesis of silver nanostructures in various morphology and the possibility of moving away from current chemical techniques towards more environmentally friendly, less hazardous, simpler, and high efficient material as antimicrobial activity and Anti-oxidant.

Increasing the antimicrobial resistance associated with S. aureus mastitis challenges the therapy of such infection and results in extensive economic losses. This study revealed an increase in the efficacy of eight different antibiotics upon their combination with polyvinylpyrrolidone-capped silver nanoparticles (PVP-AgNPs) against MDR S. aureus mastitis strain. Significant synergism was detected in PVP-AgNPs combinations with a group of antibiotics including oxytetracycline, vancomycin, ofloxacin, cefuroxime, and ampicillin/sulbactam, but the highest synergism was reported with kanamycin, chloramphenicol, and penicillin. Furthermore, the antibacterial activity of PVP-AgNPs was tested in milk compared to PBS, demonstrating that the particles remained effective against S. aureus in milk with a twofold increase in MIC compared to PBS. At a concentration of 50 μg/kg b.wt, the PVP-AgNPs showed no signs of toxicity in albino rats upon oral exposure, whereas the intraperitoneal route produced slight toxicity signs within the safety limit. Our results suggested that a strategy of combining PVP-AgNPs with antibiotics might be a magic bullet to beat S. aureus mastitis and save the dairy industry. However, further study is required to evaluate the effect in vivo using mastitis model and expand the toxicological study to include systemic absorption from mammary gland to body organs, distribution, and elimination.

Water is the cornerstone of all life. With cascading warnings of water shortages, treating wastewater to achieve the purity required for various applications ranging from irrigation of crops to its use in drinking water is critical. Both carbon dots and MOFs have attracted intense interest, and many investigations have been raised, especially concerning their function as photocatalysts. The carbon dots show great advantages: biocompatibility, ease of conducting chemical reactions to change the nature of their surface, good colloidal stability, and low cost. These good qualities give both carbon dots and organic metal frames great potential to replace the traditional catalysts currently used in treating water from organic dyes. The applications of metal-organic frameworks (MOFs), which contain photo-active sites, especially ZIF-8, in the field of photocatalysis to remove dyes as water pollutants, have been discussed. The MOFs materials prepared by bonding metal ions with the organic ligands showed superior photoactivity properties to their individual counters. This article summarizes the progress made in preparing carbon dots and summarizing the synthesis methods and emission mechanisms. We envision that the carbon dots will ultimately have significant commercial use and become a strong competitor to some fluorescent materials currently used to treat wastewater. This review provides insights into both basic research and practical applications of carbon dots.

Metal-semiconductor Nano-composites have enormous applications due to Plasmon –exciton coupling. Open aperture Z-scan is investigated for Ag–CdSe hybrid nanostructure, a toggle from saturable absorption process SA to reverse saturable absorption RSA is observed upon laser power increment. Proofs of crystal and morphological structure are given by selected area electron diffraction (SAED) and high resolution transmission electron microscope (HRTEM). Red shifting in photoluminescence spectra PL is observed which is ascribed to the particle size increment. Intriguing nonlinear findings can be used to engineer optical switching devices and optical limiters.

Needle-like cellulose nanocrystals (CNCs) were prepared from useless rice straw, which posed problems of environmental pollution in Egypt during its disposal in the burning process. Cellulose was obtained using an alkaline treatment, followed by a bleaching process and acid hydrolysis producing a high yield of CNCs ~12 ± 3 (%, w/w). Resultant CNCs were instrumentally characterized by FTIR, XRD, transmission electron microscopy (TEM), Brunauer–Emmett–Teller, and particle potential analyses; moreover, antimicrobial activity, hemolysis, and cytotoxicity were bioassessed. XRD exhibited an elevated crystallinity index of approximately 98%, and thermal decomposition of thermogravimetric analysis thermograph ranged from ~245 to 480°C. The TEM investigation showed that the nonaggregated needle-like nanocrystals diameter ranged from ~20 to 60 nm. Interestingly, CNCs at high concentrations (1,000 μg/ml) did not affect the viability of HFB-4 and WI38 human normal cell lines. Polyvinyl alcohol (PVA)/hyaluronic acid (HA) hydrogel membranes were reinforced with various concentrations of CNCs [0.25, 0.5, and 1.0% (w/v)] and prepared by the solution-casting method using citric acid as a crosslinker. The results revealed that using CNCs as nanofillers up to 0.5% enhanced dramatically the mechanical properties of membranes and exhibited good swelling capacity, biocompatibility, and antimicrobial activity, compared to hydrogel free CNCs. Therefore, the PVA/HA/CNCs membranes might have great potential in wound dressing application and it can be regarded as suitable to be developed into targeted nanocarriers or nanofillers for biomedical applications.

Fluorescence is a powerful tool in biochemistry, biophysics, forensic science, and biotechnology. Two main principal properties for any fluorophore, brightness and photostability, are fundamentally important to achieve a high level of sensitivity for detection. Therefore, improvements in the technique are strongly encouraged and pursued, such as new developments in terms of the technique sensitivity, the range of fluorophores, their stability, and the versatility of the experimental setups that help move this particular scientific research in biosensing and molecular imaging forward. Therefore, a new avenue is based on the use of plasmonic nanostructures in the enhancement of the collective photo-physical properties including their absorption and fluorescence, known as “plasmon-enhanced fluorescence.” Such plasmonic enhancement is due to the localized surface plasmon resonance at the metal surface, which leads to increasing the exciton radiative recombination rate in the fluorophore and thereby improves the signal obtained and increases sensitivity. In addition, the plasmonic enhancement might depend on several parameters such as nanoparticle size and shape, metal type, and the spectral overlap in the absorption spectra and the type and the separation distance between both plasmonic nanoparticle and the fluorophore. Throughout this chapter, previous approaches are discussed, which are devoted to tracking the influence of plasmonic nanostructures on the photoluminescence of the fluorophores especially the hybrid nanocomposites based on plasmonic/quantum dots including semiconductor and carbon-based nanoparticles. In addition, the possible applications of metal-enhanced fluorescence nanohybrids in the biological and medical applications such as imaging and biosensing techniques.

Synthesis of Au-branched CdSe nanocomposites has been reported. High resolution transmission electron microscope (HRTEM) confirms the formation of nanocomposite with a branched shape. Effect of the growth time on absorbance and photoluminescence (PL) has been presented. The nanocomposite has been utilized as a photocatalyst for methelene blue dye.

Water pollution with heavy metals poses many global challenges, especially concerning environmental sustainability, which raises more attention to the field of increasing the performance of the adsorbent materials for toxic heavy metals. This study presents the synthesis of silica nanocomposite from rice straw residues with a high surface area and activating its surface with (3-aminopropyl)triethoxysilane and 3-(trimethoxysilyl)propyl methacrylate (VNH2–SiO2), and the exploitation of acrylates group to link vinylpyrrolidone monomer to produce nontoxic polyvinylpyrrolidone-propylmethacrylate-silica nanocomposite (PVP-SiO2). FTIR and low/high angle-XRD, surface-area profiles are used to identify the properties of these materials. The BET-surface area of silica and activated silica, VNH2–SiO2, and PVP-SiO2 materials were of 985, 603, and 388 m2 g−1, with a pore diameter of 4.1, 2.8 and 2.1, respectively. The obtained PVP-SiO2 showed fast adsorption rates and good adsorption capacity of 142.8, 111, 46.08 mg/g, toward lead, copper, and nickel cations, respectively, compared to VNH2–SiO2. Strengthening the structure of silica pores with the groups of carbonyl, amine, and pyrrolidone rings has helped to enhance the adsorption of metal cations on the PVP-SiO2 nanocomposite. By applying the polymer to a sample that mimics a contaminated industrial wastewater sample, the adsorption efficiency was estimated at 99% and decreased to 96% after reuse for four times. Adsorption kinetics are well-matched with the model of pseudo-first-order, whereas the adsorption equilibrium coincided well with the Langmuir model. The calculated thermodynamic parameters (Δ G°, Δ H°, and Δ S°) indicate that the adsorption of lead, copper, and nickel ions on PVP-SiO2 was endothermic and spontaneous. The study of the possibility of material reuses demonstrated that the proposed PVP-SiO2 can be used multiple cycles without a significant reduction in the original adsorption performance.

Au and Au–CdSe nanoparticles (NPs) have been synthesized by organometallic pyrolysis method. Nano-crystals (NCs) structure was confirmed using high resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD). Nonlinear optical absorption is investigated by Z -scan technique using nanosecond laser pulses of second harmonic Nd:YAG. Intensity-dependence of nonlinear absorption on both nano-size and concentrations is reported. These are interesting findings which can be used to fabricate optical limiting and optical switching devices from NPs and hybrid systems.

Plasmonic hybrid nanostructure including Semiconductor-metallic nanoparticles, and graphene-plasmonic nanocomposites have great potential to be used as photocatalyst for hydrogen production and for photodegradation of organic waste. Also, they are potential candidate as active materials in photovoltaic devices. Plasmonic-magnetic nanocomposites could be used in photothermal therapy and biomedical imaging. This chapter will focus on the environmental impact of these materials and their in-vitro and in-vivo toxicity. In addition, the applications of these hybrid nanostructures in energy and environment will be discussed in details.

The recent extensive interest of nanostructure materials associated with their unique properties is motivated to develop new hybrid nanocomposites that couple two nano-components together in the form of Core/Shell, nanoalloys, and doped nanostructures. Hybrid nanostructure provides another opportunity for tuning the physical and chemical properties at the nanoscale. This opens the door for the discovery of new properties and potential for more applications. This chapter is devoted to present, and discuss the recent advances and progress relevance for Plasmonic hybrid nanocomposites. In addition, literature reviewed on different attempts to obtain high quality plasmonic nanocomposites via chemical routes, and their physico-chemical aspects for this class of novel nanomaterials. The authors presented their recent published work regarding Plasmonic hybrid nanostructure regarding plasmonic-semiconductor, plasmonic magnetic and plasmonic graphene nanocomposites.

A simple and robust method for power acquisition for achieving power, thermal, and momentum safety for high power-demand spacecraft uses current sensors of the solar wings rather than conventional sun sensors. The method includes a wing sun search phase, an x/z slew phase, and a safe hold phase. Solar wing current is continuously monitored against a high current threshold and a low current threshold. Wing sun search phase transitions either to x/z slew phase or safe hold phase. When solar wing current is lower than the low current threshold, the x/z slew phase is entered that slews the spacecraft about an axis in the x/z plane until solar wing current is higher than the high current threshold. When current is higher than the high current threshold, the method transitions to or remains in safe hold phase in which the spacecraft is spun about its solar wing axis. The low current persistence timer is set to be longer than the high current persistence timer in order to bias the method to prefer safe hold phase over x/z slew phase. The new method reduces cost by eliminating the need of conventional sun sensors. In addition, the new method has reduced the time-topower-safety by a factor of two, a key discriminator between saving and loss of the spacecraft.